Long Branch 2.0
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nick pine
Feb 9, 2012, 5:39:11 AM2/9/12
to sunspace, jkpr...@verizon.net, je.ba...@verizon.net, jimc...@aol.com
>After blower door testing and airsealing with a dense pack insulation retrofit, Terri's 100-year-old house (photo on page 8 of http://sbse.org/newsletter/issues/newsf08.pdf ) used 208 therms of natural gas at 95% efficiency (19.8 million Btu) and 551 kWh of electricity totaling 21.6 million Btu in January of 2011, when the average outdoor temp was 32 F, so the house conductance is now 21.6M/(65-32)/31d/24h = 881 Btu/h-F, so it would need 24h(65-36.6)881 = 600K Btu for an average 36.6 F December day near NYC.
>Indoor electrical use provided about 61K Btu, leaving a need for 538K Btu/day of solar heat in an average year, including gas water heating energy.
>PVWATTS says the southeast and southwest walls receive 685 and 701 Btu/ft^2 of sun on an average December day, with an average 40 F daytime temp and a potential solar siding gain of 0.8x685-6h(70-40)1ft^2/R2 = 458 Btu/ft^2 on the southeast and 471 for the southwest. An 8'x40' patch of SE siding would contribute 147K Btu/day, with 151K for SW. With 320 ft^2 of SE solar siding above the porch roof and 320 ft^2 of SW siding above the driveway, a solar yard boiler needs to supply (538K-147K-151K) = 240K Btu/day.
NREL says 510 Btu/ft^2 of sun falls on the ground and 860 falls on a
south wall on an average December day in NYC. A yard boiler that's L'
long and W' wide with a 10' vertical north wall (below the porch
railing height, for aesthetic reasons) and a single layer of
polyethylene film over a sloped south wall that reaches the ground
would collect Q = 0.9L(860x10+510W) Btu/day. If Q = 240K, L = W = 16'.
If we increase L to 24', Q = 362K. With minimal mesh radiation loss,
the 24'x18.9' = 453 ft^2 of poly film glazing would lose about
6(70-40)453 = 82K, with a net gain of 281K/day. But the heat store
will also lose heat to the outdoors.
Let's make L = 32' (another convenient poly film roll width) and W =
16'. Then Q = 483K Btu/day and the $35 605 ft^2 piece of poly film
loses 109K Btu, for a net gain of 374K Btu/day.
So the heat store needs about 374K/(140-70) = 5343 Btu/F of fast
thermal mass, eg 5343/0.16/2000 = 16.7 tons of stone, about 8 cubic
yards. Terri's house is near Sandy Hook, just a few miles from the
Jersey shore, so there may be a nearby round rock source.
The house needs 5dx538K = 2.7 million Btu for 5 cloudy 36.6 F December
days, eg 2.7M/(140-70) = 38571 Btu/F, eg 38571/450 = 86 55 gallon
water drums. A few years ago, I put 200 55 gallon drums in a 100'
plastic film greenhouse. A 16'x32' box could hold a single layer of
128 2'x3' tall drums. But we could make 28L'x4'Wx3'H EPDM rubber
trenches using drums and boards and stone as trench walls. Each trench
could hold 336 ft^3 (2500 gallons) of water, ie 21K Btu/F, so we could
do the whole job with 2 trenches and just a few drums.
Terri pays for municipal water and sewers now. It would be nice to
collect rainwater from the poly film roof in one trench and use the
other for high temp wastewater treatment, with an air bubbler. A few
years ago, I built a small treatment plant on my lawn, pumping 11
gallons per day from the cesspool through 2 plastic trash cans with a
heater, an air bubbler, a sand filter, and a ferric chloride drip. The
drinkable effluent met PA tertiary treatment standards, unlike most PA
municipal plants which barely met the secondary standards. As an
alternative, the cool house return water could help distill the
wastewater in a condenser. This could be useful in dry western states,
eg in Earthships.
Nick
>Indoor electrical use provided about 61K Btu, leaving a need for 538K Btu/day of solar heat in an average year, including gas water heating energy.
>PVWATTS says the southeast and southwest walls receive 685 and 701 Btu/ft^2 of sun on an average December day, with an average 40 F daytime temp and a potential solar siding gain of 0.8x685-6h(70-40)1ft^2/R2 = 458 Btu/ft^2 on the southeast and 471 for the southwest. An 8'x40' patch of SE siding would contribute 147K Btu/day, with 151K for SW. With 320 ft^2 of SE solar siding above the porch roof and 320 ft^2 of SW siding above the driveway, a solar yard boiler needs to supply (538K-147K-151K) = 240K Btu/day.
NREL says 510 Btu/ft^2 of sun falls on the ground and 860 falls on a
south wall on an average December day in NYC. A yard boiler that's L'
long and W' wide with a 10' vertical north wall (below the porch
railing height, for aesthetic reasons) and a single layer of
polyethylene film over a sloped south wall that reaches the ground
would collect Q = 0.9L(860x10+510W) Btu/day. If Q = 240K, L = W = 16'.
If we increase L to 24', Q = 362K. With minimal mesh radiation loss,
the 24'x18.9' = 453 ft^2 of poly film glazing would lose about
6(70-40)453 = 82K, with a net gain of 281K/day. But the heat store
will also lose heat to the outdoors.
Let's make L = 32' (another convenient poly film roll width) and W =
16'. Then Q = 483K Btu/day and the $35 605 ft^2 piece of poly film
loses 109K Btu, for a net gain of 374K Btu/day.
So the heat store needs about 374K/(140-70) = 5343 Btu/F of fast
thermal mass, eg 5343/0.16/2000 = 16.7 tons of stone, about 8 cubic
yards. Terri's house is near Sandy Hook, just a few miles from the
Jersey shore, so there may be a nearby round rock source.
The house needs 5dx538K = 2.7 million Btu for 5 cloudy 36.6 F December
days, eg 2.7M/(140-70) = 38571 Btu/F, eg 38571/450 = 86 55 gallon
water drums. A few years ago, I put 200 55 gallon drums in a 100'
plastic film greenhouse. A 16'x32' box could hold a single layer of
128 2'x3' tall drums. But we could make 28L'x4'Wx3'H EPDM rubber
trenches using drums and boards and stone as trench walls. Each trench
could hold 336 ft^3 (2500 gallons) of water, ie 21K Btu/F, so we could
do the whole job with 2 trenches and just a few drums.
Terri pays for municipal water and sewers now. It would be nice to
collect rainwater from the poly film roof in one trench and use the
other for high temp wastewater treatment, with an air bubbler. A few
years ago, I built a small treatment plant on my lawn, pumping 11
gallons per day from the cesspool through 2 plastic trash cans with a
heater, an air bubbler, a sand filter, and a ferric chloride drip. The
drinkable effluent met PA tertiary treatment standards, unlike most PA
municipal plants which barely met the secondary standards. As an
alternative, the cool house return water could help distill the
wastewater in a condenser. This could be useful in dry western states,
eg in Earthships.
Nick
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